My colleagues have answered in a very thorough way - and I hesitate to add anything accept this: women's voices are important in this discussion and thus I will add mine. I can't speak for all women and I do not deny that men are affected by abortion. Men, however, can never undergo the procedure - only women can. This does not preclude insightful reflection from anyone, male or female, but it is striking to me that one often speaks of abortion as being only about the status of the fetus and not an issue that affects the woman who is considering the question. Why is this important? In my view, there are many morally regrettable moments in a person's life - some of which involve difficult decisions and many choices involve regret. Why would a woman choose to terminate a pregnancy? Do we imagine that women (generally) do not take this to be a morally charged decision? For some, the moral clarity about abortion as a wrong action will preclude them from making that choice. Other women discover...

Ontology is always in the mind of the person contemplating the nature of being, so I applaud your agnostic stance. Beneath your question lies a very important question: what is the role of science in philosophy and morals? Our ability to visualize the tiniest gametes meet to form a zygote is a wondrous thing indeed. But science cannot provide ontological insight on the matter; it can only trace its trajectory toward becoming a fetus or not based on conditions in the uterine and hormonal environment. The fetus (9 weeks gestation and beyond) has overcome many obstacles, but again, its ontological status is elusive at best. I don't believe "potentiality" can be a claim of ontological status, but I'll defer to my colleagues who study Aristotle or Thomas Aquinas and Natural Law. But it seems to me there is a very risky step made by those who would accord person-hood status to the fetus. What is the presumption? Because science can observe the various stages of embryonic development, we suddenly "know...